1. Field of the Invention
The present invention relates to electronic components and more specifically to electronic components each including first to third LC parallel resonators.
2. Description of the Related
As an invention related to a conventional electronic component, a laminated band pass filter described in International Publication No. WO 2009/041294 is known, for example. The laminated band pass filter includes first to third LC parallel resonators. The first LC parallel resonator includes a first inductor electrode that is opened on the left side and shaped like a square-cornered U. The second LC parallel resonator includes a second inductor electrode that is opened on the right side and shaped like a square-cornered U. The first inductor electrode and the second inductor electrode are in a line-symmetric relationship.
The third LC parallel resonator includes a third inductor electrode. The third inductor electrode is located farther down on the lower side than the first inductor electrode and the second inductor electrode, and when viewed from above in a plane, overlaps the first inductor electrode and the second inductor electrode. A first region surrounded by the first inductor electrode and the third inductor electrode and a second region surrounded by the second inductor electrode and the third inductor electrode are equal in area. The above-described first to third LC parallel resonators constitute the band pass filter.
In the laminated band pass filter described in International Publication No. WO 2009/041294, the characteristic impedance viewed from an input/output terminal on the side of the first LC parallel resonator and the characteristic impedance viewed from an input/output terminal on the side of the third LC parallel resonator deviate from each other. More specifically, the first region surrounded by the first inductor electrode and the third inductor electrode and the second region surrounded by the second inductor electrode and the third inductor electrode are equal in area. This causes the strength of magnetic coupling between the first inductor electrode and the third inductor electrode and the strength of magnetic coupling between the second inductor electrode and the third inductor electrode to be similar to each other.
One end of the third inductor electrode is electrically coupled to a ground electrode. A portion that surrounds the first region is positioned near one end of the third inductor electrode. Thus, in the portion that is included in the third inductor electrode and surrounds the first region, inductive coupling is strong. In contrast, the other end of the third inductor electrode is electrically coupled to a capacitor electrode. A portion that surrounds the second region is positioned near the other end of the third inductor electrode. Thus, in the portion that is included in the third inductor electrode and surrounds the second region, capacitive coupling is strong. Accordingly, the magnetic coupling between the first inductor electrode and the third inductor electrode is stronger than the magnetic coupling between the second inductor electrode and the third inductor electrode. As a result, in the laminated band pass filter described in International Publication No. WO 2009/041294, the characteristic impedance viewed from the input/output terminal on the side of the first LC parallel resonator and the characteristic impedance viewed from the input/output terminal on the side of the third LC parallel resonator deviate from each other.